problem with hydrangea paniculata....

9 years ago

Hello!

I have recently planted three hydrangea paniculata quick fire plants. Within two days of planting them, most of the leaves have black streaks on them. The soil in which these are planted have had a history of black spot that affected my roses. Furthermore, I did add some espoma soil acidifier – that contains sulfur – to alleviate the black spot in the soil. Any idea what these black streaks are? Is it a fungus, or could it be a result of sulfur toxicity? The soil pH is around 6.

Also, I have a nearby quick fire that has been established for about three years now. The leaves have a rust color all over them. I thought maybe it was the same infection. Is this common for these plants to get this affliction?

Any help you can offer would be greatly appreciated! I am including pictures of the above mentioned situations.

Featured Answer

NHBabs z4b-5a NH

9 years ago

It doesn't look fungal to me. Is the top photo your established one? To me it looks like a bit of stress, perhaps water stress. I don't know about the darker areas on the new plants are, perhaps also stress caused since it is new plantings. However, the black spot that affects roses won't infect the hydrangeas since foliar fungus is specific to particular plants and a rose isn't closely related to hydrangeas.

Where are you? How much sun do these plants get?

IME Hydrangea paniculata cultivars, including QF, have really no disease issues in my garden.

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Comments (7)

Johnny Jauss
Original Author
9 years ago
Thank you for your help! The top one is an established plant - the other pictures are from newly planted QF plants - there are now quite a few leaves yellowing on the bottom of each plant and dropping off - so it could be transplant shock.

I am in St. Louis, where it is quite warm and humid, and they get about 4-6 hours of afternoon sun a day - the flowers have browned considerably since planting, and the stems have dark streaks through them now as well.

I will keep an eye on them and report back as they progress - I really appreciate your perspective!
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October_Gardens
9 years ago
The yellowing of bottom leaves means too much water in nearly all cases. If you see yellowing/dropping of leaves on a regular basis, you'll also notice a general lack of sun and a lot of rain, or else you're watering too much.
Johnny Jauss thanked October_Gardens
NHBabs z4b-5a NH
9 years ago
I would actually check the soil moisture on the new plants, both in the original potting mix root ball and in the surrounding soil. Is the soil in both places moist, not really squishy wet or really dry when you stick a finger in several inches down? Here I don't water mine at all after the first year or two since they don't like it too wet. The best way to tell if it's too wet or dry is to actually check.

You could also rig temporary shade screens for the new plants to give them a bit of a break - a strategically placed lawn chair or a couple of bamboo poles to hold a sheet or pillowcase, set so that there is shade during the most intense sun and heat of the day.
Johnny Jauss thanked NHBabs z4b-5a NH
Johnny Jauss
Original Author
9 years ago
The surrounding native soil - not the potting mix root ball - is moist. The sun rigging is a great idea, since I do have a habit of overwstering, since the sun is so intense and hot here in St. Louis. The plants wilt easily.
NHBabs z4b-5a NH
9 years ago
"The surrounding native soil - not the potting mix root ball - is moist."

Since most of the roots are still in the potting mix root ball on new plants, the moisture level of the potting mix is important. If you haven't checked it, you should. Sometimes potting mixes get dried out and don't rewet well, and the texture change from the root ball to the native soil can hinder water movement between the two.
Johnny Jauss thanked NHBabs z4b-5a NH
Johnny Jauss
Original Author
9 years ago
Got it - I was just getting ready to ask if the difference in moisture between the two mattered. Thank you!